Dark forces at work

[unixronin]

This XKCD strip, and the "dark flow" astronomical discovery it reports, raise a very interesting issue.

Current conventional wisdom in physics says that the gravitational force is carried by a particle of some kind, and propagates no faster than C.  Conventional wisdom in physics also says that because of this, objects beyond the edge of the observable universe cannot affect us gravitationally, as gravitational force carriers from them can never reach us (any more than their light can).

If every galaxy we can observe, regardless of direction, is being pulled towards one region of the sky, and if this is the action of a supermassive object beyond the edge of the observable universe, it would imply that the conventional wisdom is not the case, and gravity is not in fact limited to the speed of light.

To say the least, the possible implications of this revelation would be interesting.

Comments

[smandal.livejournal.com]

A few issues here:

* Not everyone is happy with the methodology used by those reporting this result. We'll see how that shakes out, and the finer data from the upcoming Planck satellite may give a clear-cut answer.

* You can have superluminal disturbances in Einstein gravity, but not in the Newtonian limit. There are theories of modified gravity with superluminal perturbations, but they have other defects that make them untenable.

* An alternative explanation consistent with Einstein gravity is that disturbances during an era of cosmic inflation might not have been symmetric. Part of this disturbance is now outside our horizon, creating this "dark flow."

[unixronin.livejournal.com]

Not everyone is happy with the methodology used by those reporting this result. We'll see how that shakes out, and the finer data from the upcoming Planck satellite may give a clear-cut answer.

Yeah. Note the generous use of "if" and "would". :)